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Original Investigation
October 2018

Nondaily Smokers’ Changes in Cigarette Consumption With Very Low-Nicotine-Content Cigarettes: A Randomized Double-blind Clinical Trial

Author Affiliations
  • 1Department of Psychology, University of Pittsburgh, Pittsburgh, Pennsylvania
  • 2UPMC Hillman Cancer Center, Pittsburgh, Pennsylvania
  • 3Department of Biostatistics, University of Pittsburgh, Pittsburgh, Pennsylvania
JAMA Psychiatry. 2018;75(10):995-1002. doi:10.1001/jamapsychiatry.2018.1831
Key Points

Question  Do nondaily smokers decrease cigarette consumption when switched from their own brand to very low-nicotine-content cigarettes (VLNCC) compared with identical normal-nicotine-content cigarettes (NNCC)?

Findings  In this randomized double-blind clinical trial with 238 randomized participants, the mean cigarettes per day was reduced significantly more in the VLNCC group (1.6 cigarettes per day, 51% of baseline) than in the NNCC group (0.05 cigarettes per day, 2% of baseline).

Meaning  Like daily smokers, switching to VLNCCs causes nondaily smokers to reduce their cigarette consumption, although it does not necessarily cause them to stop smoking.

Abstract

Importance  The US Food and Drug Administration is considering limiting cigarettes to very low nicotine levels. Cigarette consumption of nondaily intermittent smokers (ITS), who compose one-third of US adult smokers, could feasibly increase or could be unaffected if their smoking is not motivated by nicotine seeking.

Objective  To compare cigarette consumption in ITS receiving very low-nicotine-content cigarettes (VLNCCs) or identical normal-nicotine-content cigarettes (NNCCs).

Design, Setting, and Participants  This randomized double-blind clinical trial was conducted from June 2015 to July 2017 at a single US site. Volunteer ITS not planning to quit were recruited via media. Overall, 297 individuals enrolled, and 238 were randomized. Analyses were intent-to-treat.

Interventions  After a 2-week baseline of smoking their own brand of cigarettes provided gratis, ITS were randomized to VLNCCs or NNCCs for 10 weeks.

Main Outcomes and Measures  The number of cigarettes per day (CPD) was assessed by real-time reporting, timeline follow-back reports, and cigarette butt counts. The primary outcome was change in CPD from baseline to weeks 9 to 10 of intervention, adjusting for baseline CPD.

Results  The mean (SD) age of the 238 randomized participants was 37.9 (13.8) years. Of 238 participants, 108 (45%) were men. At baseline, the mean (SD) CPD was 3.1 (2.9). In intent-to-treat analyses using multiple imputation to address missing data, the VLNCC group had a mean decrease of 1.6 CPD (95% CI, 1.1-2.0; 51% of baseline) vs 0.05 decrease with NNCCs (95% CI, −0.5 to 0.4; 2% of baseline). Treatment group differences were not materially moderated by sex, race/ethnicity, or history of daily smoking. Cheating with conventional cigarettes, inferred from cotinine assays, was more common in the VLNCC group (OR, 2.95; 95% CI, 1.54-5.66), but sensitivity analyses showed significant VLNCC effects among the compliant participants as well. In longitudinal analysis of CPD over time with random intercept and slope, the VLNCC and NNCC groups differed significantly in both linear (−0.15; 95% CI, −0.22 to −0.08; P < .001) and quadratic (0.0026; 95% CI, 0.0010-0.0042; P = .002) trends: CPD dropped by 43.8% in the VLNCC group over 4 weeks, then leveled off thereafter. Abstinence (intent-to-treat, biochemically verified) in weeks 9 to 10 postrandomization did not differ significantly by treatment group (VLNCC, 10.2% vs NNNC, 5.0%; P = .28).

Conclusions and Relevance  Switching to VLNCCs caused substantial smoking reduction among ITS but did not significantly increase abstinence. Response to a VLNCC intervention suggests that nicotine-seeking motivates ITS’ smoking.

Trial Registration  ClinicalTrials.gov Identifier: NCT02228824

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